Nasa will end attempts by its Insight lander to dig down into the soil on Mars after concluding that it had not been able to gain the friction it needed to do so.
HP3 is a 40cm-long pile driver connected to the lander by a tether with embedded temperature sensors.
But after getting the top of the mole about 2 or 3 centimetres under the surface, the team tried one last time to use a scoop on InSight’s robotic arm to scrape soil onto the probe and tamp it down to provide added friction.
After the probe conducted 500 additional hammer strokes on Saturday with no progress, the team called an end to their efforts.
Nevertheless, Insight can still carry out valuable scientific experiments after Nasa recently extended its mission until December 2022.
“We’ve given it everything we’ve got, but Mars and our heroic mole remain incompatible,” said HP3’s principal investigator, Tilman Spohn.
“Fortunately, we’ve learned a lot that will benefit future missions that attempt to dig into the subsurface.”
While Nasa’s Phoenix lander scraped the top layer of the Martian surface, no mission before InSight has tried to burrow into the soil. Doing so is important for a variety of reasons including the possibility that future astronauts may need to dig through soil to access water ice, while scientists want to study the subsurface’s potential to support microbial life.
“We are so proud of our team who worked hard to get InSight’s mole deeper into the planet. It was amazing to see them troubleshoot from millions of miles away,” said Nasa’s Thomas Zurbuchen.
“This is why we take risks at Nasa – we have to push the limits of technology to learn what works and what doesn’t. In that sense, we’ve been successful.”
The unexpected properties of the soil near the surface next to InSight will be puzzled over by scientists for years to come. The mole’s design was based on soil seen by previous Mars missions – soil that proved very different from what the mole encountered. For two years, the team worked to adapt the unique and innovative instrument to these new circumstances.
There’s much more science to come from InSight, along with hunting for Marsquakes, the likes of which were first detected in 2019, the lander hosts a radio experiment that is collecting data to reveal whether the planet’s core is liquid or solid.